Abstract
The unique crystallization properties of the antenna protein C-phycocyanin (C-PC) from the thermophilic cyanobacterium Thermosynechococcus elongatus are reported and discussed. C-PC crystallizes in hundreds of significantly different conditions within a broad pH range and in the presence of a wide variety of precipitants and additives. Remarkably, the crystal dimensions vary from a few micrometres, as used in serial crystallography, to several hundred micrometres, with a very diverse crystal morphology. More than 100 unique single-crystal X-ray diffraction data sets were collected from randomly selected crystals and analysed. The addition of small-molecule additives revealed three new crystal packings of C-PC, which are discussed in detail. The high propensity of this protein to crystallize, combined with its natural blue colour and its fluorescence characteristics, make it an excellent candidate as a superior and highly adaptable model system in crystallography. C-PC can be used in technical and methods development approaches for X-ray and neutron diffraction techniques, and as a system for comprehending the fundamental principles of protein crystallography.
Highlights
Protein X-ray crystallographic techniques have been used extensively to determine static macromolecular structures and to analyse protein dynamics (Liebschner, 2018; Spence, 2017)
C-PC crystallizes in hundreds of significantly different conditions within a broad pH range and in the presence of a wide variety of precipitants and additives
This study focuses on examining the robust crystallization of C-phycocyanin (C-PC), which is almost independent of the composition of the crystallization solution, and investigating the resulting crystal morphology, molecular packing and crystal quality
Summary
Protein X-ray crystallographic techniques have been used extensively to determine static macromolecular structures and to analyse protein dynamics (Liebschner, 2018; Spence, 2017). High-quality protein crystals are necessary to achieve electron-density maps of high resolution and high confidence, which allow the study of molecular mechanisms and of the function and interactions of biomacromolecules (Liebschner, 2018; Chayen, 2009). The crystallization abilities of the latter protein have been well studied, involving different space groups, crystal morphologies and sizes for the development of multiple applications (Panjikar et al, 2015; Meents et al, 2017; Haas, 2020). The antenna protein C-PC appears to be an essential sample for methods development in protein crystallography In combination with their optical properties, blue colour and strong fluorescence, C-PC crystals may inspire new applications and studies in biomolecular crystallography
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
